The first step for drywalling stairs will be to know how
the stair hand railing is going to finish. If the stair hand railing is
going to get wood edging or skirt boards this will require the drywall
to be finished in a certain way. As you can see in this picture the
drywall hangers allowed for a wood handrail at the lower stair stringer.
You can tell this by the way the drywall is cut, knowing that the side of the stairs will get finished with a 1 x 12 piece of trim they don't have to be as precise with their cuts as if they were going to wrap carpet around the edge of the steps.